Control for a room air conditioner



Dec. 22, 1959 w. w. DAVIS 2,917,904

CONTROL FOR A ROOM AIR CONDITIONER Filed Dec. 17, 1956 /.\Z Y /Z4 \l F1g.

WWWIHI-Illlllltfll gmllmilmimmmmnmmumummmlunmmummlmu Ji g 13 da k UnitedStates Patent O CONTROL FOR A ROOM AIR CONDITIONER William w. Davis,Prospect Heights, in.

Application December 17, 1956, Serial No. 628,620

3 Claims. (Cl. 62-162) This invention relates to air conditioning unitsof the type usually mounted in the outside window of a room for thepurpose of introducing co'oled outside air and cooled recirculated airto the room or merely recirculating the room air without cooling it.More particularly, the invention pertains to electrical means for fullycontrolling any of' the above functions manually or automatically.

In conventional room air conditioners including a motor drivenrefrigerating compressor and a motor driven room air circulating fan itis customary to arrange the electrical controls for obligating thecirculating fan to run continually when the controls are set on coolwhether or not the compressor is undergoing a cooling cycle in' responseto a signal from the room thermostat. Although this scheme isadvantageous when the room is occupied, since it enhances comfort of theoccupants by assuring constant agitation of the room air, it alsoresults inunnecessary expenditure of power by the fan motor when theunit is set on cool and the room is unoccupied. Thus, it is desirablethat a control means be provided which enables a choice of whether thecirculating fan shall step when the compressor stops or whether thecirculating fan shall run continually when the compressor is notefiectively cooling. With this choice available, a room may be kept coolWithout wasting power while the room is unoccupied, and when re-entered,the feeling of comfort incident to circulating the room air can bealmost instantly attained by starting the circulating fan and allowingit to run continually during ensuing cooling cycles.

It is therefore a primary object of this invention to provide'an airconditioner control scheme and apparatus that enables a choice ofwhether the fan motor and compressor motor are to both cease operationwhen the room thermostat no longer calls for cooling or whether the fanis to run continually under this condition. I

A further object is the provision of a room air conditioner control thatpermits selection of a cooling cycle, subject to the control of athermal responsive means in the form of a room thermostat, or in thealternative, selection of an air recirculating cycle without cooling butwith an additional choice of running the circulating fan either undercontrol of the thermostat or under manual control.

A more general object is to provide a room air conditioner with acontrol means allowing optimum versatility in selection of the cycle tobe performed but which is electrically and mechanically simplified andwhich is economical to make and install.

Other specific objects will be perceptible throughout the course of thisspecification.

A more explicit description of the invention will now be set forth inconjunction with the drawing in which: Fig. 1 is a horizontal,sectional, plan view of an exemplary ro'om air conditioner embodying thenovel control means;

Fig. 2 is a front elevational view of the apparatus illustrated in Fig.1, partly in section; and,

Fig. 3 is a diagram of the electrical control circuit constituting theinvention.

Before entering into a detailed discussion of the novel arrangement forcontrolling the operational sequence of an air conditioner, features ofa typical unit to which the invention may be applied will be brieflyoutlined primarily in reference to Figs. 1 and 2 of the drawing.

The illustrative air conditioner may be of conventional design in therespect that it includes a motor driven refrigeration compressor 11, acondenser coil 12 and an evaporator or cooling coil 13. Condenser coil12 has a sheet metal conical shroud 14 for directing air that isdelivered by a heat rejecting condenser fan 15 to the outsideatmosphere. Refrigerating compressor 11 includes an electrical primemover in the form of a motor 21, see Fig. 3.

A two speed motor 16 is provided for driving the condenser fan 15 aswell as an evaporator or room air circulating fan 17 of the centrifugaltype. Both fans are keyed for joint rotation to a double ended motorshaft 18. Air passing through cooling coil 13 under the influence ofcirculating fan 17 is compelled to pass through a purifying filter .19under all circumstances.

The components thus far recited are all located within a sheet metalhousing designated by the reference numeral 20. Ordinarily there is anadditional decorative casing over housing 20 but the casing has herebeen omitted for the sake of brevity. 7

Housing 20 is subdivided into a number of compartments for the purposeof separating the components of the unit and enabling control over theflow of air in various directions through the housing. The firstcompartment, defined by a longitudinally disposed wall or bulkhead 22,is a fresh air inlet chamber 23 communicating with the atmospherethrough a screened opening 24. A second compartment 25, containingcompressor 11, condenser 12 and fan motor 16, is defined by housing 20,longitudinal wall 22 and a transverse wall 26. Wall 26 is imperforateexcept where motor shaft 18 penetrates it for supporting centrifugal fan17. A constant supply of outside air is assured through compartment 25by provision of additional screened openings 27 located outside thesymbolized wall 28 of the room being conditioned.

A third principal cooling section is subdivided into a number ofadditional compartments primarily by a transverse wall 29 located behindevaporator coil 13. Wall 29 ties in by means of its curved bottom 30with Wall 26 back of it to define a scroll chamber 31 in whichcentrifugal fan 17 is housed. Wall 29 has an inlet hole 32 for admittingto fan 17 air that has passed through filter 19 and cooling coil 13. Airis discharged from fan 17 to the ro'om being cooled through a duct 33lying in a horizontal plane, see Fig. 2.

Ahead of filter 19, extending vertically from the base 37 of the unit toa height substantially equal to cooling coil 13, there is a transversecompartment 34 that is defined by a front wall 36 having a large opening'35 therethrough. Compartment 34 is further provided with a shortvertically apertured wall 38 that separates co'mpartrnent 34 from freshair compartment 23 and condenser compartment 25. 7

Note that the three last named compartments junction in the vicnity of arotary damper 42 that permits placing any two of the compartments incommunication at one time. Damper 42 comprises a segment 43 molded o'rformed with'a pair of disks 44 and 45 at its upper and lower ends,respectively. A shaft 46, journaled at its bottom end in base 37 forexample and having a manual positioning knob 47 at its upper end,extends through the damper for selecting positions of the latter.

The position of damper segment 43 in the illustrative examplecorresponds with a condition where air is drawn from the room under theinfluence of fan 17, filtered, and discharged again to the room Withoutadmixture of fresh air. If refrigerating compressor 11 is running underthis condition, coil 13 will be cold and cooled air will be dischargedto the room. If the compressor is not running, fan 17 will merelyrecirculate room air. Note, however, that when segment 43 is in itsillustrated position that fresh air compartment 23 and condensercompartment 25 are interconnected. Thus, condenser fan 25 may draw freshair in addition to that obtainable through opening 27 for augmentingrejection of heat through. condenser coil 12.

If segment 43 is manually rotated approximately one hundred and twentyangular degrees clockwise it blocks off compartment 25 and interconnectscompartments 23 and 34 for mixing fresh air with the room air beingcirculated by fan 17.

If segment 43 is rotated counterclockwise through the same angle it willblock off fresh air inlet 23 and interconnect compartments 25 and 34.Under this circumstance, part of the room air will be circulated by fan17, as described above, and part will be exhausted to the outsideatmosphere under the influence of condenser fan 14.

The methods of directing air flow just described are functionally wellestablished in the art and constitute no part of the instant inventionexcept insofar as they bear a relation to the novel means forcontrolling operation of the fan motor 16 and the refrigerating unit 11together with its prime mover 21.

Before proceeding with a description of the structural and functionalintricacies of the novel air conditioner control scheme, the generalpurposes sought to be achieved and the terminology to be employed willbe considered. It has been already indicated that the occupants of theroom may desire that room air be merely recirculated by circulating fan17, with or without addition of fresh air through damper 42, and withcompressor 11 deactivated so that no cooling takes place. This is to beknown as an air circulating cycle. It will appear hereinafter that inaccordance with the invention the operator may choose to place thecirculating fan under control of a room thermostat or under manualon-off control by means of depressing appropriate push buttons. It willappear below that the circulating cycle may be selected by depressingpush buttons marked Hi Fan or L Fan together with a button marked eitherT On or T Off.

Another operating condition governab'le from a selector or push buttonstation is that called a cooling cycle Where the refrigeratingcompressor motor runs periodically subject to a signal received from aroom thermostat and Where under the prior art arrangements the continualoperation of the circulating fan is obligatoly regardless of whether thethermostat has attained its off temperature. In contrast, the inventionallows the operator to elect whether the circulating fan and compressormotor are to stop simultaneously when a room temperature condition hasbeen satisfied or Whether the fan is to continue operating during acooling cycle. To make this choice according to the invention, theoperator merely needs to depress a button marked Hi Cool or L0 Cool, toestablish a cooling cycle, and one or the other of two buttons forcutting the thermostat in or out of the fan circuit, marked T On and TOff.

Attention is now invited to Fig. 3 Where there is schematicallyrepresented compressor motor 21, high and low speed circulating fanmotor 16, a bellows type room thermostat 55' a push button stationindicated generally by the numeral 51, and a source of electric poweridentified as line wires L and L Push button station 51 may be locatedat any convenient place such as suggested in Figs. 1 and 2. Thermostat50 may be placed anywhere in the room being cooled but is is preferablyclosely associated with the appparatus depicted in the same figures, thewhole apparatus thereby being self-contained.

Those versed in the art will appreciate that the push button station 51may take the form of a rotary type multi-position switch or acombination of a rotary switch and push buttons, the term multi-positionswitch perhaps being the most accurate generic designation for anycombination suggested.

inviting attention to Fig. 3, the multiple control station 51 includesseven push buttons, in this example, the five top ones of which areinterlocked as symbolized by the dashed line 52 and the lower two ofwhich are interlocked as symbolized by numeral 53. The lower two buttonsare independent of the others and are marked T On and T Off; if one isdepressed the other will automatically retract. Likewise, among theother group of five, if one is depressed the others retract and if theOff button is depressed others in that group clear any electricalconnections they may have been accomplishing.

Contacts of the selector station 51 are indicated by the referencenumerals 2-6. The contacts may be con sidered to be of the self-openingspring leaf type adapted to be held closed when any push button isdepressed by means of a cross arm such as 54, for example. The contactsare in circuit with other components so that if a cooling cycle isselected, either Hi Cool or Lo Cool buttons may be depressed for closingcontact 2 and energizing the compressor motor 21 from line 2; If Hi Coolis depressed, for example, both contacts 2 and 4 close to engerize thecompressor motor 21 and the high speed winding of fan motor 16. If theLo Cool button is depressed both contacts 2 and 3 close to energize thecompressor motor 21 and the low speed winding of fan motor 16. Whether,during a cooling cycle, the fan motor 16 is to stop along withcompressor motor 21 when room thermostat 50 opens depends upon which oneof the thermostat control circuit contacts 5 or 6 has been closed bydepressing either button T On or T OK. This will be more fully explainedshortly hereinafter.

if an air recirculating cycle is to be selected, that is, with nocooling, either Lo Fan or Hi Fan buttons may be depressed for onlyclosing contacts 3 or 4, one at a time, and thereby energizing fan motor16 at low or high-speed without accompanying refrigeration due toinactivity of refrigerator compressor motor 21.

Note that one side of each fan contact 3 and 4 is con nected to a commonwire 55 which in turn connects to one side of each thermostat contact 5and 6. Whencontact 5 is closed, during a circulating cycle, inconjunction with either closing of contacts 3 or 4, the fan motorcircuit is completed to line 1 by interposing thermostat 5G in serieswith the fan through jumper wires 56, 57. This places the fan underautomatic con trol of thermostat 5t) during the circulating cycle. However, if contact 6 is closed during a circulating cycle, interlockedcontact 5 opens, and the fan circuit is completed directly to line 1through 6 so that thermostat 50 is by-passed. In this event, fan motor16 is under man ual control because the fan motor may be stopped bypressing the Off button and started at will by pressing T Off button andHi Fan or L0 Fan.

During a cooling cycle, thermostat 50' is always in circuit at leastwith the compressor motor 21 in order to prevent its constant operationwhen room temperature requirements are met. This can be realized bydepressing the L0 Cool button, for example, and tracing a circuit from Lthrough compressor motor 21, contact 2, thermostat lead wire 57 andthermostat 50, to L1; Thus, only opening of room temperature responsivethermostat 50 will stop the compressor motor 21 during a cooling cycle.

According to the invention, however, and for reasons stated very earlyin this specification, it is also possible to exercise an option ofhaving fan motor 16 stop along with compressor motor 21 or to requirethe fan motor to run continually though the compressor has stopped. If,during a cooling cycle, it is desired to run the fan motor 16continually while the compressor has cut out, the operator must depressone Cool button and close contact 6 by depressing T Off. This connectsfan motor 16 to L by means of lead 58 directly.

If, during a cooling cycle, it is desired to have the fan motor 16 stopwhen compressor 21 stops, the operator must depress one Cool button andclose contact 5 by depressing T On. This completes the fan motor circuitfrom common wire 55, through contact 5, jumpers 56, 57, and throughthermostat 50 to line 1. Thus, the thermostat interrupts the fan andcompressor circuits simultaneously.

Although represented as the bellows type, thermostat 50 may take anyform such as the well known bimetal type. thermostat with snap actingproperties have been omitted for the sake of brevity.

The invention may be summarized by pointing out that the novelself-contained air conditioner control scheme allows selection of anyfunction that an air conditioner could heretofore accomplish. Inaddition, the novel control permits the compressor and fan to operatejointly in response to the room thermostat or permits the fan only to bestopped by the thermostat during a cooling cycle. Moreover, during anair circulating cycle, the novel control scheme permits placing thecirculating fan under independent manual or thermostatic control.

Although a preferred embodiment of the invention has been described, thedisclosure is to be considered illustrative rather than limiting, forthe invention may be variously embodied and is to be interpreted inscope according to the claims which follow.

It is claimed:

1. For conditioning the air of a room having a room air conditioner ofthe window mounted type having an evaporator, condensing unit and primemover therefor and a room air circulating fan and a motor therefor,thermal responsiveelectric circuit opening and closing means in heatexchange relation with the air of the room being air conditioned, afirst circuit comprising a first manually operable multi-positionelectric switch adapted to selectively energize said prime mover from asource of electric energy for effecting a room cooling cycle andalternately to en'- ergize said fan for effecting a room air circulatingcycle while said prime mover is de-energized, and a second circuitcomprising a second manually operable multi-position electric switchadapted to energize said prime mover and said fan motor under concurrentcontrol of said thermal responsive means and alternately to energizeonly said prime mover under control of said thermal responsive meansduring a cooling cycle, said second circuit and second multi-positionswitch also being adapted to selectively energize said fan under controlof said thermal responsive means during a room air circulating cycle.

Further, conventional elements impressing the 2. For conditioning theair of a room having a room air conditioner of the window mounted typehaving an evaporator, condensing unit and prime mover therefor and aroom air circulating fan and a motor therefor, thermal responsiveelectric circuit opening and closing means in heat exchange relationwith the air of the room being air conditioned, a first circuitcomprising a first manually operable multi-position electricswitch'connected to selectively energize said prime mover from a sourceof electric energy for efiecting a room cooling cycle, and a secondcircuit comprising a second manually operable multi-position switchconnected to selectively energize said circulating fan motor underindependent control of said thermal responsive means when said primemover is de-energized and alternately energize said circulating fanmotor under dependent control of said second switch when said primemover is de-energized.

3. For conditioning the air of a room having a room air conditioner ofthe window mounted type having an evaporator, condensing unit and anelectrical prime mover therefor and a fan for circulating cooled airinto the room and a motor therefor, thermal responsive electric circuitopening and closing means exposed to room air temperature, a firstcircuit comprising a first manually operable multiposition switchadapted to connect said prime mover and said fan motor to a source ofelectric energy to efiect a room cooling cycle when in one switchposition and adapted to alternately connect independent of said primemover said fan motor to said source of energy when in another switchposition to effect an air circulating cycle, a second circuit comprisinga second manually operable multi-position switch mechanicallyindependent of said first switch adapted for connecting said source ofelectric energy with said thermal responsive means in series circuitwith said fan motor and said prime mover when said first switch ispositioned for effecting a cooling cycle whereby both said fan and saidprime mover are de-energized when said thermal responsive means attainsa predetermined temperature during said cooling cycle, said secondcircuit and said second switch being adapted for connecting said thermalresponsive means in series relation with said prime mover and saidsource of electric energy when said second switch is in an alternateposition during a cooling cycle, and said second circuit and secondswitch being adapted to connect said thermal responsive means in seriesrelation with said fan motor and said source of electric energy duringan air circulating cycle whereby said fan motor may be controlledindependently of said prime mover.

References Cited in the file of this patent UNITED STATES PATENTS969,781 Geissinger Sept. 13, 1910 2,140,305 Ashley Dec. 13, 19382,516,093 Ruff July 18, 1950 2,778,197 Legeza Jan. 22, 1957 2,840,667Atchison June 24, 1958

